A finish for melt-spun elastic fiber containing amino-modified silicones is described in Japanese Patent Laid-Open No. Sho 61-97471. A finish for elastic fiber containing both polyether-modified silicones and amino-modified silicones is described in Japanese Patent Laid-Open No. Hei 4-5277. A finish for elastic fiber containing organic phosphate salts is described in Japanese Patent Laid-Open No. Hei 7-173770.
Those conventional finishes cannot impart sufficient antistaticity to elastic fiber because they are formulated with hydrophobic base components, such as silicone oils, mineral oils and ester oils. Excessive stickiness at the contact between elastic fiber yarn strands causes poor unwinding performance of the elastic fiber yarn from packages. Improper friction at the contact between elastic fiber yarn strands causes poor package buildup. Optimum lubricity on yarn surface is necessary for constant operation in down-stream processes. In the knitting operation of elastic fiber yarn combined with cotton spun yarn, cotton fly is apt to stick on elastic fiber yarn and deposit at a clearer guide that must be frequently cleaned to prevent ends down of elastic fiber yarn.
A finish containing a phosphate ester, alkyl amine having primary or secondary amino groups, and amino-modified silicone may be effective for preventing elastic fiber yarn strands from sticking to each other, because those components react with isocyanates contained in polyurethane polymer forming elastic fiber yarn and thus inhibit the reaction between isocyanates on the surface of elastic fiber yarn, the cause of the sticking of elastic fiber yarn strands. The alkyl amines and amines contained in the amino-modified silicones may irritate skin and must be carefully handled. The phosphate esters are almost ineffective by themselves for imparting antistaticity, lubricity, and package buildup performance and inhibiting cotton fly sticking on elastic fiber yarn.
The object of the present invention is to provide the finishes for elastic fiber, which attain superior antistaticity, lubricity, and unwinding and package buildup performances of elastic fiber yarn, minimize cotton fly sticking on elastic yarn in knitting or weaving of elastic fiber yarn and cotton yarn, and attain high-speed knitting operation, for example, with 100 m/min or higher yarn feeding speed, of fine elastic yarn, for example, monofilament of 33 dtex or finer, and cotton yarn; and the elastic fiber produced therewith.